A wide variety of conveying equipment is used to stack bulk material such as gravel, coal, sand, grain, wood waste, dirt and other particulate. Such equipment often is in the form of a belt-type conveyor system, which is able to convey bulk material from crushing and/or screening equipment to create one or more stockpiles or stacks. The stockpiles may take the form of individual conical stacks but more often take the form of an array of stacks formed through the use of so-called radial stackers that can swing radially from side-to-side. Other stackers may be in the form of telescoping stackers, which may also be radial stackers and which are sometimes able to form larger and higher stacks.
Radial stackers have in recent years been designed to be portable. Portable stackers use a carriage having wheels or tracks that are typically mounted to support the power source, usually an internal combustion engine, which provides hydraulic power to the working components of the stacker. Drive pulleys, reduction gearing and clutch assemblies are typically positioned adjacent the engine. When wheeled carriages are used, the conveyor can be pulled down the highway by a tractor instead of having to be loaded onto a flat-bottomed trailer, which is normally the case with tracked carriages. In order to shorten the length and the height of the stacker, the front and/or the rear ends of the stacker are often designed to be folded over one another.
While these stacker designs have proven very popular and successful for many operations, two inherent drawbacks exist with such designs. First, the weight of the engine is centrally disposed, and this limits the height or length of the conveyor because otherwise the front end of the stacker might become unstable and perhaps even topple over. This in turn limits the angle of extension and thus the height of the stack. This issue is addressed in part in McCloskey's U.S. Pat. No. 6,129,196, which is incorporated herein by reference. Second, with the heaviest portion of the stacker, the carriage-mounted engine and its fuel tank, is disposed well away from the fifth wheel of the tractor that is pulling the stacker down the highway. This can result in less stability, which may limit the speed and the type of roads over which the stacker can be pulled. A third drawback is that as the front and/or rear of the stacker is folded over for transport to another site, the size of the engine, the drive pulleys and the reduction gearing assembly prohibits the folding conveyor to fold as low as it could if the engine was not there or was relocated. This may limit the length of the conveyor or otherwise diminish its size, possible resulting in a reduction the capacity of the stacker or, again, a reduction in the size of the stack formed by the stacker. This sometimes forces the manufacturer to use a less powerful, electric-driven system, which may require batteries or an electric power source.
Finally, because the size of the engine, drive pulleys and reduction gearing varies greatly from unit to unit, the mounting of these drive components has often required customized mountings, increasing the cost of fabrication and complicating modular fabrication and assembly or rendering such impossible. Examples of such prior art units can be seen in U.S. Pat. No. 4,135,614 (FIG. 3), U.S. Pat. No. 6,360,876 (FIG. 2), and U.S. Pat. No. 8,584,826 (FIG. 1).